The present invention relates to a down-hole separator for a production well and, more particularly to a concentric chamber separator through which flowing hydrocarbons are passed from a producing formation in order to separate gas from liquid hydrocarbons prior to production of the liquid hydrocarbons through a production tubing.
As hydrocarbons are produced from hydrocarbon producing wells, substantial amounts of gas, which are in solution with the oil due to the temperature and pressure conditions of the formation, come out of solution during the course of their transport to the surface. Large amounts of such gas can cause inefficient operation of and damage to pumps which are designed primarily for moving liquids. Furthermore, gas can collect in various places along the production line to create a condition known as "gas lock" which can effectively block the gravity flow of oil. This "gas lock" can also cause significant damage to pumps located along the production line.
Various devices have been proposed whereby down-hole separation of oil and gas is accomplished through manipulation of the difference in density between the two fluids.
U.S. Pat. No. 3,386,390 discloses a gas anchor for down-hole separation. Separation is accomplished through a concentric chamber attachment that extends from the bottom of a tubing.
U.S. Pat. No. 4,074,763 discloses a down-hole separator which employs centrifugal force to achieve the desired separation of gas from oil.
U.S. Pat. No. 4,676,308 discloses a down-hole separator located in a production tube wherein both oil and gas drawn into the production tube are circulated through an annulus between the tube and well casing where gas rises to the surface and oil re-enters the tube.
Devices as those described above encounter problems in operation when the oils being produced are of medium or heavier weight due to increased viscosity which interferes with liberation of gas to be separated. When formation pressures are low, turbulence sufficient to separate gas from oil, and particularly heavy oil, is not achieved. This is in part due to the fact that the oil and gas are originally produced either into the tubing or the annular space which both have relatively large flow area. Hence, the flow velocities of the oil/gas fluids may not be sufficient to provide the desired degree of separation.
Accordingly, it is a principal object of the present invention to provide a down-hole separator which will remove substantial amounts of gas from a hydrocarbon stream before the hydrocarbon stream passes through a down-hole pump.
It is a further object of the present invention to provide a down-hole separator having an outside diameter equal to or less than the outside diameter of the production tubing to facilitate production operations which must be carried out in the annular space of the producing well.
Further objects and advantages will become apparent to those skilled in the art after a consideration of the following drawings and detailed description of the invention.